Fix Objective-C++ Sret of non-trivial data types on Windows ARM64 (#88671)

Linked to https://github.com/gnustep/libobjc2/pull/289.

More information can be found in issue: #88273.

My solution involves creating a new message-send function for this
calling convention when targeting MSVC. Additional information is
available in the libobjc2 pull request.

I am unsure whether we should check for a runtime version where
objc_msgSend_stret2_np is guaranteed to be present or leave it as is,
considering it remains a critical bug. What are your thoughts about this
@davidchisnall?

(cherry picked from commit 3dcd2cca)